题目： Whether the three methods to stop snakeheads from spreading is feasible.
阅读： The reading raises three methods to stop the spread of snakehead fish because it threatens the ecosystem.
1. Making laws to prevent people from transporting snakehead fish. Some people in the fish market will illegally transport or release unsold snakehead fish.
2. Educating fishers to catch snakehead. If they recognize that people actually can eat snakehead as a food source, they will catch many to eat and to sell.
3. Researching some poison to kill the snakehead. Though poison will also kill native fishes in the river, people can restock native fishes.
The listening contradicts all methods proposed by the author of the passage and points out their potential problems.
1. Even if people do not transport the snakehead, the spread will still continue. The reason is that there are already many snakeheads, and these snakeheads will move to other rivers even without human's efforts, because they can live and move on land as long as they are moist.
2. Educating fishers to catch snakehead will not help stop the spread of snakehead. Conversely, it may lead to the increase of snakehead. Because
when fishers realize they can make profit by catching snakehead, they will introduce snakehead to other water bodies and raise snakehead in order tocatch more snakehead, even this is illegal.
3. It is true that native fishes can be restocked; however, poison will also kill some insects and micro organisms, which cannot be restocked. So, native fishes that feed on these insects and micro organisms cannot grow to their original size. This is irreversible.